Sorafenib: 10 years after the first pivotal trial

Novel pyrazolo[3,4-d]pyrimidine derivatives: design, synthesis, anticancer evaluation, VEGFR-2 inhibition, and antiangiogenic activity

A novel series of 12 pyrazolo[3,4-d]pyrimidine derivatives were created and evaluated in vitro for their antiproliferative activity against the NCI 60 human tumor cell line panel. Compounds 12a-d displayed significant antitumor activity against MDA-MB-468 and T-47D (breast cancer cell lines), especially compound 12b, which exhibited the highest anticancer activity against MDA-MB-468 and T-47D cell lines with IC50 values of 3.343 ± 0.13 and 4.792 ± 0.21 μM, respectively compared to staurosporine with IC50 values of 6.358 ± 0.24 and 4.849 ± 0.22 μM. The most potent cytotoxic derivatives 12a-d were studied for their VEGFR-2 inhibitory activity to explore the mechanism of action of these substances. Compound 12b had potent activity against VEGFR-2 with an IC50 value of 0.063 ± 0.003 μM, compared to sunitinib with IC50 = 0.035 ± 0.012 μM. Moreover, there was an excellent reduction in HUVEC migratory potential that resulted in a significant disruption of wound healing patterns by 23% after 72 h of treatment with compound 12b. Cell cycle and apoptosis investigations showed that compound 12b could stop the cell cycle at the S phase and significantly increase total apoptosis in the MDA-MB-468 cell line by 18.98-fold compared to the control. Moreover, compound 12b increased the caspase-3 level in the MDA-MB-468 cell line by 7.32-fold as compared to the control.

Aryl azoles based scaffolds for disrupting tumor microenvironment

Thirty-nine aryl azoles, thirteen triazoles and twenty-seven tetrazoles, have been synthetized and biologically evaluated to determine their activity as tumor microenvironment disruptors. Antiproliferative studies have been performed on tumor cell lines HT-29, A-549 and MCF-7 and on non-tumor cell line HEK-293. It has been studied in HT-29 the expression levels of biological targets which are involved in tumor microenvironment processes, such as PD-L1, CD-47, c-Myc and VEGFR-2. In addition, antiproliferative activity was evaluated when HT-29 were co-cultured with THP-1 monocytes and the secretion levels of IL-6 were also determined in these co-cultures. The angiogenesis effect of some selected compounds on HMEC-1 was also evaluated as well as their action against vasculogenic mimicry on HEK-293. Compounds bearing an amino group in the phenyl ring and a halogen atom in the benzyl ring showed promising results as tumor microenvironment disrupting agents. The most outstanding compound decrease dramatically the population of HT-29 cells when co-cultured with THP-1 monocytes and the levels of IL-6 secreted, as well as it showed moderate effects over PD-L1, CD-47 and c-Myc.

Design and synthesis of novel hexahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivatives as potential anticancer agents with antiangiogenic activity via VEGFR-2 inhibition, and down-regulation of PI3K/AKT/mTOR signaling pathway

New thieno[2,3-d]pyrimidine derivatives were designed and synthesized. The National Cancer Institute (NCI) evaluated the synthesized novel compounds against a panel of 60 tumor cell lines for their antiproliferative activity. Compounds 6b, 6f, and 6g showed potent anticancer activity at 10 µM dose, with mean GI of 20.86%, 76.41%, and 31.49%, respectively. Compound 6f was selected for five-dose concentrations evaluation. Compound 6f scored a submicromolar range of GI50 values against 10 cancer cell lines, indicating broad-spectrum and potent antiproliferative activity. Compound 6f TGI values were recorded in the cytostatic range of 4.02-95.1 µM. In comparison to sorafenib, the tested compounds 6b, 6f, and 6g inhibited VEGFR-2 with IC50 values of 0.290 ± 0.032, 0.066 ± 0.004, and 0.16 ± 0.006 µM, correspondingly. Compound 6f significantly reduced the total VEGFR-2 expression and its phosphorylation. Additionally, 6f reduced the phosphorylation of PI3K, Akt, and mTOR pathway proteins. Moreover, the migratory potential of HUVECs was significantly reduced, after 72 h of treatment with compound 6f, resulting in disrupted wound healing patterns which verified the angiogenesis suppression properties of compound 6f. Compound 6f increased the total apoptosis percentage by 21.27-fold compared to sorafenib, which caused a 24.11-fold increase in the total apoptosis percentage. This apoptotic activity was accompanied by a 7.81-fold increase in the level of apoptotic caspase-3. Furthermore, the cell cycle analysis revealed that the target derivative 6f reduced cellular proliferation and induced an arrest in HCT-15 colon cancer cell cycle at the S phase. Molecular modeling was used to determine the binding profile and affinity of derivative 6f toward the VEGFR-2 active site.

Inhibition of LPAR6 overcomes sorafenib resistance by switching glycolysis into oxidative phosphorylation in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most threatening tumours in the world today. Pharmacological treatments for HCC mainly rely on protein kinase inhibitors, such as sorafenib and regorafenib. Even so, these approaches exhibit side effects and acquired drug resistance, which is an obstacle to HCC treatment. We have previously shown that selective lysophosphatidic acid receptor 6 (LPAR6) chemical antagonists inhibit HCC growth. Here, we investigated whether LPAR6 mediates resistance to sorafenib by affecting energy metabolism in HCC. To uncover the role of LPAR6 in drug resistance and cancer energy metabolism, we used a gain-of-function and loss-of-function approach in 2D tissue and 3D spheroids. LPAR6 was ectopically expressed in HLE cells (HLE-LPAR6) and knocked down in HepG2 (HepG2 LPAR6-shRNA). Measurements of oxygen consumption and lactate and pyruvate production were performed to assess the energy metabolism response of HCC cells to sorafenib treatment. We found that LPAR6 mediates the resistance of HCC cells to sorafenib by promoting lactic acid fermentation at the expense of oxidative phosphorylation (OXPHOS) and that the selective LPAR6 antagonist 9-xanthenyl acetate (XAA) can effectively overcome this resistance. Our study shows for the first time that an LPAR6-mediated metabolic mechanism supports sorafenib resistance in HCC and proposes a pharmacological approach to overcome it.

Sorafenib targets and inhibits the oncogenic properties of endometrial cancer stem cells via the RAF/ERK pathway

Background

Distinct subsets of cancer stem cells (CSCs) drive the initiation and progression of malignant tumors via enhanced self-renewal and development of treatment/apoptosis resistance. Endometrial CSC-selective drugs have not been successfully developed because most endometrial cell lines do not contain a sufficient proportion of stable CSCs. Here, we aimed to identify endometrial CSC-containing cell lines and to search for endometrial CSC-selective drugs.

Methods

We first assessed the presence of CSCs by identifying side populations (SPs) in several endometrial cancer cell lines. We then characterized cell viability, colony-formation, transwell invasion and xenotransplantion capability using the isolated SP cells. We also conducted real-time RT-PCR, immunoblot and immunofluorescence analyses of the cells’ expression of CSC-associated markers. Focusing on 14 putative CSC-selective drugs, we characterized their effects on the proliferation and apoptosis of endometrial cancer cell lines, examining cell viability and annexin V staining. We further examined the inhibitory effects of the selected drugs, focusing on proliferation, invasion, expression of CSC-associated markers and tumor formation.

Results

We focused on HHUA cells, an endometrial cancer cell line derived from a well-differentiated endometrial adenocarcinoma. HHUA cells contained a sufficient proportion of stable CSCs with an SP phenotype (HHUA-SP). HHUA-SP showed greater proliferation, colony-formation, and invasive capabilities compared with the main population of HHUA cells (HHUA-MP). HHUA-SP generated larger tumors with higher expression of proliferation-related markers, Ki67, c-MYC and phosphorylated ERK compared with HHUA-MP when transplanted into immunodeficient mice. Among the 14 candidate drugs, sorafenib, an inhibitor of RAF pathways and multiple kinase receptors, inhibited cell proliferation and invasion in both HHUA-SP and -MP, but more profoundly in HHUA-SP. In vivo treatment with sorafenib for 4 weeks reduced the weights of HHUA-SP-derived tumors and decreased the expression of Ki67, ZEB1, and RAF1.

Conclusions

Our results suggest that HHUA is a useful cell line for discovery and identification of endometrial CSC-selective drugs, and that sorafenib may be an effective anti-endometrial cancer drug targeting endometrial CSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02888-y.

Hydrogen Bonds, Topologies, Energy Frameworks and Solubilities of Five Sorafenib Salts

Sorafenib (Sor) is an oral multi-kinase inhibitor, but its water solubility is very low. To improve its solubility, sorafenib hydrochloride hydrate, sorafenib hydrobromide and sorafenib hydrobromide hydrate were prepared in the mixed solvent of the corresponding acid solution, and tetrahydrofuran (THF). The crystal structures of sorafenib hydrochloride trihydrate (Sor·HCl.3H₂O), 4-(4-{3-[4-chloro-3-(trifluoro-methyl)phenyl]ureido}phenoxy)-2-(N-methylcarbamoyl) pyridinium hydrochloride trihydrate, C₂₁H₁₇ClF₃N₄O₃⁺·Cl^-.3H₂O (I), sorafenib hydrochloride monohydrate (Sor·HCl.H₂O), C₂₁H₁₇ClF₃N₄O₃⁺·Cl^-.H₂O (II), its solvated form (sorafenib hydrochloride monohydrate monotetrahydrofuran (Sor·HCl.H₂O.THF), C₂₁H₁₇ClF₃N₄O₃⁺·Cl^-.H₂O.C₄H₈O (III)), sorafenib hydrobromide (Sor·HBr), 4-(4-{3-[4-chloro-3-(trifluoro-methyl)phenyl]ureido}phenoxy)-2-(N-methylcarbamoyl) pyridinium hydrobromide, C₂₁H₁₇ClF₃N₄O₃⁺·Br^- (IV) and sorafenib hydrobromide monohydrate (Sor·HBr.H₂O), C₂₁H₁₇ClF₃N₄O₃⁺·Br^-.H₂O (V) were analysed. Their hydrogen bond systems and topologies were investigated. The results showed the distinct roles of water molecules in stabilizing their crystal structures. Moreover, (II) and (V) were isomorphous crystal structures with the same space group P2₁/n, and similar unit cell dimensions. The predicted morphologies of these forms based on the BFDH model matched well with experimental morphologies. The energy frameworks showed that (I), and (IV) might have better tabletability than (II) and (V). Moreover, the solubility and dissolution rate data exhibited an improvement in the solubility of these salts compared with the free drug.

Impact of Crystal Habit on the Dissolution Rate and In Vivo Pharmacokinetics of Sorafenib Tosylate

The dissolution rate is the rate-limiting step for Biopharmaceutics Classification System (BCS) class II drugs to enhance their in vivo pharmacokinetic behaviors. There are some factors affecting the dissolution rate, such as polymorphism, particle size, and crystal habit. In this study, to improve the dissolution rate and enhance the in vivo pharmacokinetics of sorafenib tosylate (Sor-Tos), a BCS class II drug, two crystal habits of Sor-Tos were prepared. A plate-shaped crystal habit (ST-A) and a needle-shaped crystal habit (ST-B) were harvested by recrystallization from acetone (ACN) and n-butanol (BuOH), respectively. The surface chemistry of the two crystal habits was determined by powder X-ray diffraction (PXRD) data, molecular modeling, and face indexation analysis, and confirmed by X-ray photoelectron spectroscopy (XPS) data. The results showed that ST-B had a larger hydrophilic surface than ST-A, and subsequently a higher dissolution rate and a substantial enhancement of the in vivo pharmacokinetic performance of ST-B.

Treatment of liver cancer cells with ethyl acetate extract of Crithmum maritimum permits reducing sorafenib dose and toxicity maintaining its efficacy

OBJECTIVES

Hepatocellular carcinoma (HCC) is one of the most frequent tumours worldwide and available drugs are inadequate for therapeutic results and tolerability. Hence, novel effective therapeutic tools with fewer side effects are of paramount importance. We have previously shown that Crithmum maritimum ethyl acetate extract exerts a cytostatic effect in HCC cells. Here, we tested whether C. maritimum ethyl acetate extract in combination with half sorafenib IC50 dose ameliorated efficacy and toxicity of sorafenib in inhibiting liver cancer cell growth. Moreover, we investigated the mechanisms involved.

METHODS

Two HCC cell lines (Huh7 and HepG2) were treated with C. maritimum ethyl acetate extract and half IC50 sorafenib dose usually employed in vitro. Then, cell proliferation, growth kinetics and cell toxicity were analysed together with an investigation of the cellular mechanisms involved, focusing on cell cycle regulation and apoptosis.

KEY FINDINGS

Results show that combined treatment with C. maritimum ethyl acetate extract and half IC50 sorafenib dose decreased cell proliferation comparably to full-dose sorafenib without increasing cell toxicity as confirmed by the effect on cell cycle regulation and apoptosis.

CONCLUSIONS

These results provide scientific support for the possibility of an effective integrative therapeutic approach for HCC with fewer side effects on patients.

Aryl Urea Based Scaffolds for Multitarget Drug Discovery in Anticancer Immunotherapies

Twenty-one styryl and phenethyl aryl ureas have been synthetized and biologically evaluated as multitarget inhibitors of Vascular endothelial growth factor receptor-2 VEGFR-2 and programmed death-ligand-1 (PD-L1) proteins in order to overcome resistance phenomena offered by cancer. The antiproliferative activity of these molecules on several tumor cell lines (HT-29, MCF-7, HeLa and A549), on the endothelial cell line human microvascular endothelial cells (HMEC)-1 and on the non-tumor cell line human embryonic kidney cells (HEK)-293 has been determined. Some derivatives were evaluated for their antiangiogenic properties such as their ability to inhibit microvessel formation using HMEC-1 or their effect on VEGFR-2 in both cancer and endothelial cell lines. In addition, the immunomodulator action of a number of selected compounds was also studied on PD-L1 and c-Myc proteins. Compounds 16 and 23 (Z) and (E)-styryl p-bromophenyl urea, respectively, showed better results than sorafenib in down-regulation of VEGFR-2 and also improved the effect of the anti-PD-L1 compound BMS-8 on both targets, PD-L1 and c-Myc proteins.

Sirtuin 1 and 2 inhibitors enhance the inhibitory effect of sorafenib in hepatocellular carcinoma cells

Multidrug resistance (MDR) counteracts the efficiency of sorafenib, an important first-line therapy for hepatocellular carcinoma (HCC). Sirtuins (SIRTs) 1 and 2 are associated with tumor progression and MDR. We treated 2D and 3D cultures (which mimic the features of in vivo tumors) from HCC cells with sorafenib alone or in the presence of SIRTs 1 and 2 inhibitors (cambinol or EX-527; combined treatments). Cultures subjected to combined treatments showed a greater fall in cellular viability, proliferation (PCNA, cyclin D1 and Ki-67 expression and cell cycle analysis), migration and invasion when compared with cultures treated only with sorafenib. Similarly, combined treatments produced more apoptosis (annexin V/PI, caspase-3/7 activity) than sorafenib alone. Since cell cycle dysregulation and apoptotic blockage are reported mechanisms of MDR, the modulation found in PCNA, cyclin D1, Ki-67 and caspase-3/7 proteins by cambinol and EX-527 are probably playing a role in enhancing the sensitivity of HCC cell lines to sorafenib. EX-527 reduced MRP3 and BCRP expression in sorafenib-treated HCC cells. Since ABC transporters contribute to MDR, MRP3 and BCRP could be also influencing in the response of HCC cells to sorafenib. Overall, 2D and 3D cultures behave similarly except that 3D cultures were less sensitive to treatments, reinforcing the clinical relevance of the current study. Findings presented in this manuscript support a potential application for SIRTs 1 and 2 inhibitors since we demonstrated that these compounds enhance the inhibitory effect of sorafenib upon treatment of hepatocellular carcinoma cells lines.

The perplexity of targeting genetic alterations in hepatocellular carcinoma

Genetic heterogeneity is a well-recognized feature of hepatocellular carcinoma (HCC). The coexistence of multiple genetic alterations in the same HCC nodule contributes to explain why gene-targeted therapy has largely failed. Targeting of early genetic alterations could theoretically be a more effective therapeutic strategy preventing HCC. However, the failure of most targeted therapies has raised much perplexity regarding the role of genetic alterations in driving cancer as the main paradigm. Here, we discuss the methodological and conceptual limitations of targeting genetic alterations and their products that may explain the limited success of the novel mechanism-based drugs in the treatment of HCC. In light of these limitations and despite the era of the so-called "precision medicine," prevention and early diagnosis of conditions predisposing to HCC remain the gold standard approach to prevent the development of this type of cancer. Finally, a paradigm shift to a more systemic approach to cancer is required to find optimal therapeutic solutions to treat this disease.

Lenvatinib and sorafenib for differentiated thyroid cancer after radioactive iodine: a systematic review and economic evaluation

BACKGROUND

Thyroid cancer is a rare cancer, accounting for only 1% of all malignancies in England and Wales. Differentiated thyroid cancer (DTC) accounts for ≈94% of all thyroid cancers. Patients with DTC often require treatment with radioactive iodine. Treatment for DTC that is refractory to radioactive iodine [radioactive iodine-refractory DTC (RR-DTC)] is often limited to best supportive care (BSC).

OBJECTIVES

We aimed to assess the clinical effectiveness and cost-effectiveness of lenvatinib (Lenvima®; Eisai Ltd, Hertfordshire, UK) and sorafenib (Nexar®; Bayer HealthCare, Leverkusen, Germany) for the treatment of patients with RR-DTC.

DATA SOURCES

EMBASE, MEDLINE, PubMed, The Cochrane Library and EconLit were searched (date range 1999 to 10 January 2017; searched on 10 January 2017). The bibliographies of retrieved citations were also examined.

REVIEW METHODS

We searched for randomised controlled trials (RCTs), systematic reviews, prospective observational studies and economic evaluations of lenvatinib or sorafenib. In the absence of relevant economic evaluations, we constructed a de novo economic model to compare the cost-effectiveness of lenvatinib and sorafenib with that of BSC.

RESULTS

Two RCTs were identified: SELECT (Study of [E7080] LEnvatinib in 131I-refractory differentiated Cancer of the Thyroid) and DECISION (StuDy of sorafEnib in loCally advanced or metastatIc patientS with radioactive Iodine-refractory thyrOid caNcer). Lenvatinib and sorafenib were both reported to improve median progression-free survival (PFS) compared with placebo: 18.3 months (lenvatinib) vs. 3.6 months (placebo) and 10.8 months (sorafenib) vs. 5.8 months (placebo). Patient crossover was high (≥ 75%) in both trials, confounding estimates of overall survival (OS). Using OS data adjusted for crossover, trial authors reported a statistically significant improvement in OS for patients treated with lenvatinib compared with those given placebo (SELECT) but not for patients treated with sorafenib compared with those given placebo (DECISION). Both lenvatinib and sorafenib increased the incidence of adverse events (AEs), and dose reductions were required (for > 60% of patients). The results from nine prospective observational studies and 13 systematic reviews of lenvatinib or sorafenib were broadly comparable to those from the RCTs. Health-related quality-of-life (HRQoL) data were collected only in DECISION. We considered the feasibility of comparing lenvatinib with sorafenib via an indirect comparison but concluded that this would not be appropriate because of differences in trial and participant characteristics, risk profiles of the participants in the placebo arms and because the proportional hazard assumption was violated for five of the six survival outcomes available from the trials. In the base-case economic analysis, using list prices only, the cost-effectiveness comparison of lenvatinib versus BSC yields an incremental cost-effectiveness ratio (ICER) per quality-adjusted life-year (QALY) gained of £65,872, and the comparison of sorafenib versus BSC yields an ICER of £85,644 per QALY gained. The deterministic sensitivity analyses show that none of the variations lowered the base-case ICERs to < £50,000 per QALY gained.

LIMITATIONS

We consider that it is not possible to compare the clinical effectiveness or cost-effectiveness of lenvatinib and sorafenib.

CONCLUSIONS

Compared with placebo/BSC, treatment with lenvatinib or sorafenib results in an improvement in PFS, objective tumour response rate and possibly OS, but dose modifications were required to treat AEs. Both treatments exhibit estimated ICERs of > £50,000 per QALY gained. Further research should include examination of the effects of lenvatinib, sorafenib and BSC (including HRQoL) for both symptomatic and asymptomatic patients, and the positioning of treatments in the treatment pathway.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017055516.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Postoperative adjuvant sorafenib improves survival outcomes in hepatocellular carcinoma patients with microvascular invasion after R0 liver resection: a propensity score matching analysis

BACKGROUND

Microvascular invasion (MVI) is a major determinant of survival outcome for hepatocellular carcinoma (HCC). This study aimed to investigate the efficacy of postoperative adjuvant Sorafenib (PA-Sorafenib) in HCC patients with MVI after R0 liver resection (LR).

METHODS

The data of patients who underwent R0 LR for HCC with histologically confirmed MVI at the Eastern Hepatobiliary Surgery Hospital were retrospectively analyzed. The survival outcomes for patients who underwent PA-Sorafenib were compared with those who underwent R0 LR alone. Propensity score matching (PSM) analysis was performed.

RESULTS

728 HCC patients had MVI in the resected specimens after R0 resection, with 581 who underwent LR alone and 147 patients who received in additional adjuvant sorafenib. PSM matched 113 patients in each of these two groups. The overall survival (OS) and recurrence free survival (RFS) were significantly better for patients in the PA-sorafenib group (for OS: before PSM, P = 0.003; after PSM, P = 0.007), (for RFS: before PSM, P = 0.029; after PSM, P = 0.001), respectively. Similar results were obtained in patients with BCLC 0-A, BCLC B and Child-Pugh A stages of disease.

CONCLUSIONS

PA-Sorafenib was associated with significantly better survival outcomes than LR alone for HCC patients with MVI.

Enhanced antitumour effect for hepatocellular carcinoma in the advanced stage using a cyclodextrin-sorafenib-chaperoned inclusion complex

Hepatocellular carcinoma (HCC) is a hypervascular tumour characterized by tumour-driven neovascularization. The degrees of blood oxygen saturation (DBOS), microvessel density (MVD) and tumour size (TS) are indicators in identifying the development stage of HCC. Herein, we proposed an HCC staging model using HepG2 tumour-bearing mice based on DBOS, MVD and TS. According to the patterns of these three criteria, HCC was classified into four stages: early, intermediate, advanced and end stages. The advanced stage was characterized by MVD of 50-90 (number per mm²), DBOS of 12-16% and TS of 250-600 mm³, which poses a critical challenge in HCC therapy. In order to efficiently control and treat HCC in the advanced stage, we developed a cyclodextrin (CD)-based chaperoned inclusion complex using Sorafenib (Sor), β-CD and γ-CD (SCD) via the co-crystallization method. The structural study manifested that CDs could encapsulate Sor with the hydrophobic cavities at a 1 : 1 stoichiometry ratio. The crystallographic analysis indicated that Sor-β-CD presented a diagonal stacking pattern, while Sor-γ-CD possessed a channel-type structure. The resultant chaperoned inclusion complexes significantly improved the solubility, dissolution rate and drug release of Sor, leading to superior pharmacokinetics, biodistribution and biosafety through oral administration. The antitumour effect was then evaluated on a mouse model with advanced HCC through oral administration and intratumour injection. The treatment involving the oral administration of SCDs showed a promising therapeutic effect on advanced HCC, which efficiently blocked angiogenesis and inhibited tumour progression. For the treatments using intratumour injections, only Sor-γ-CD exhibited a satisfactory anti-tumour effect with reduction in TS, MVD and DBOS. The enhanced therapeutic performance of Sor-γ-CD was attributed to its channel-type structure, which had an impact on the dissociation and release of the drug. Thus, Sor-γ-CD can be used as a potential pro-drug for clinical medicine and basic research to treat HCC.

The strange case of AMPK and cancer: Dr Jekyll or Mr Hyde? †

The AMP-activated protein kinase (AMPK) acts as a cellular energy sensor. Once switched on by increases in cellular AMP : ATP ratios, it acts to restore energy homeostasis by switching on catabolic pathways while switching off cell growth and proliferation. The canonical AMP-dependent mechanism of activation requires the upstream kinase LKB1, which was identified genetically to be a tumour suppressor. AMPK can also be switched on by increases in intracellular Ca2+, by glucose starvation and by DNA damage via non-canonical, AMP-independent pathways. Genetic studies of the role of AMPK in mouse cancer suggest that, before disease arises, AMPK acts as a tumour suppressor that protects against cancer, with this protection being further enhanced by AMPK activators such as the biguanide phenformin. However, once cancer has occurred, AMPK switches to being a tumour promoter instead, enhancing cancer cell survival by protecting against metabolic, oxidative and genotoxic stresses. Studies of genetic changes in human cancer also suggest diverging roles for genes encoding subunit isoforms, with some being frequently amplified, while others are mutated.

ABC Transporters: Regulation and Association with Multidrug Resistance in Hepatocellular Carcinoma and Colorectal Carcinoma

For most cancers, the treatment of choice is still chemotherapy despite its severe adverse effects, systemic toxicity and limited efficacy due to the development of multidrug resistance (MDR). MDR leads to chemotherapy failure generally associated with a decrease in drug concentration inside cancer cells, frequently due to the overexpression of ABC transporters such as P-glycoprotein (P-gp/MDR1/ABCB1), multidrug resistance-associated proteins (MRPs/ABCCs), and breast cancer resistance protein (BCRP/ABCG2), which limits the efficacy of chemotherapeutic drugs. The aim of this review is to compile information about transcriptional and post-transcriptional regulation of ABC transporters and discuss their role in mediating MDR in cancer cells. This review also focuses on drug resistance by ABC efflux transporters in cancer cells, particularly hepatocellular carcinoma (HCC) and colorectal carcinoma (CRC) cells. Some aspects of the chemotherapy failure and future directions to overcome this problem are also discussed.

Antisense Oligonucleotides Targeting Angiogenic Factors as Potential Cancer Therapeutics

Cancer is one of the leading causes of death worldwide, and conventional cancer therapies such as surgery, chemotherapy, and radiotherapy do not address the underlying molecular pathologies, leading to inadequate treatment and tumor recurrence. Angiogenic factors, such as EGF, PDGF, bFGF, TGF-β, TGF-α, VEGF, endoglin, and angiopoietins, play important roles in regulating tumor development and metastasis, and they serve as potential targets for developing cancer therapeutics. Nucleic acid-based therapeutic strategies have received significant attention in the last two decades, and antisense oligonucleotide-mediated intervention is a prominent therapeutic approach for targeted manipulation of gene expression. Clinical benefits of antisense oligonucleotides have been recognized by the U.S. Food and Drug Administration, with full or conditional approval of Vitravene, Kynamro, Exondys51, and Spinraza. Herein we review the scope of antisense oligonucleotides that target angiogenic factors toward tackling solid cancers.

Recent advances in molecular targeted therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second most common cause of mortality from any type of cancer, and its mortality has risen in recent years in China. Because of its insidious onset, rapid progression, and poor prognosis, HCC has become a hot and difficult research topic. HCC therapy, especially the use and research of molecular targeted drugs, has achived significant advances and opened up a new avenue for the treatment of HCC. In this paper, we will describe the recent advances in the research of of signaling pathways and potential molecular targets, the clinical use of molecular targeted drugs, and new molecular targeted drugs for HCC.

Transferrin receptor-targeted HMSN for sorafenib delivery in refractory differentiated thyroid cancer therapy

Background

Thyroid cancer becomes the most common endocrine cancer with the greatest growing incidence in this decade. Sorafenib is a multikinase inhibitor for the treatment of progressive radioactive iodine-refractory differentiated thyroid cancer (DTC), while the off-target toxicity effect is usually inconvenient for patients taking.

Methods

In this study, hollow mesoporous silica nanoparticles (HMSNs) with transferrin modification (Tf-HMSNs) were loaded with sorafenib (sora@Tf-HMSNs) to help targeted delivery of sorafenib. Due to the biocompatible Tf shell, Tf-HMSNs exhibited excellent bio-compatibility and increased intracellular accumulation, which improved the targeting capability to cancer cells in vitro and in vivo.

Results

Sora@Tf-HMSNs treatment exhibited the strongest inhibition effect of res-TPC-1 cells and res-BCPAP cells compared with sora@HMSNs and sorafenib groups and induced more cancer cell apoptosis. Finally, Western blot analysis was conducted to check the expression of RAF/MEK/ERK signaling pathway after sorafenib encapsulated Tf-HMSNs treatment.

Conclusion

Overall, sora@Tf-HMSNs can significantly increase the effective drug concentration in cancer cells and thus enhance the anticancer effect, which are expected to be promising nanocarriers to deliver anticancer drugs for effective and safe therapy for RAI-refractory DTC.

Evaluating Uncertainty in Signaling Networks Using Logical Modeling

Systems biology studies the structure and dynamics of biological systems using mathematical approaches. Bottom-up approaches create models from prior knowledge but usually cannot cope with uncertainty, whereas top-down approaches infer models directly from data using statistical methods but mostly neglect valuable known information from former studies. Here, we want to present a workflow that includes prior knowledge while allowing for uncertainty in the modeling process. We build not one but all possible models that arise from the uncertainty using logical modeling and subsequently filter for those models in agreement with data in a top-down manner. This approach enables us to investigate new and more complex biological research questions, however, the encoding in such a framework is often not obvious and thus not easily accessible for researcher from life sciences. To mitigate this problem, we formulate a pipeline with specific templates to address some research questions common in signaling network analysis. To illustrate the potential of this approach, we applied the pipeline to growth factor signaling processes in two renal cancer cell lines. These two cell lines originate from similar tissue, but surprisingly showed a very different behavior toward the cancer drug Sorafenib. Thus our aim was to explore differences between these cell lines regarding three sources of uncertainty in one analysis: possible targets of Sorafenib, crosstalk between involved pathways, and the effect of a mutation in mammalian target of Rapamycin (mTOR) in one of the cell lines. We were able to show that the model pools from the cell lines are disjoint, thus the discrepancies in behavior originate from differences in the cellular wiring. Also the mutation in mTOR is not affecting its activity in the pathway. The results on Sorafenib, while not fully clarifying the mechanisms involved, illustrate the potential of this analysis for generating new hypotheses.

Autophagic cell death associated to Sorafenib in renal cell carcinoma is mediated through Akt inhibition in an ERK1/2 independent fashion

OBJECTIVES

To fully clarify the role of Mitogen Activated Protein Kinase in the therapeutic response to Sorafenib in Renal Cell Carcinoma as well as the cell death mechanism associated to this kinase inhibitor, we have evaluated the implication of several Mitogen Activated Protein Kinases in Renal Cell Carcinoma-derived cell lines.

MATERIALS AND METHODS

An experimental model of Renal Cell Carcinoma-derived cell lines (ACHN and 786-O cells) was evaluated in terms of viability by MTT assay, induction of apoptosis by caspase 3/7 activity, autophagy induction by LC3 lipidation, and p62 degradation and kinase activity using phospho-targeted antibodies. Knock down of ATG5 and ERK5 was performed using lentiviral vector coding specific shRNA.

RESULTS

Our data discard Extracellular Regulated Kinase 1/2 and 5 as well as p38 Mitogen Activated Protein Kinase pathways as mediators of Sorafenib toxic effect but instead indicate that the inhibitory effect is exerted through the PI3K/Akt signalling pathway. Furthermore, we demonstrate that inhibition of Akt mediates cell death associated to Sorafenib without caspase activation, and this is consistent with the induction of autophagy, as indicated by the use of pharmacological and genetic approaches.

CONCLUSION

The present report demonstrates that Sorafenib exerts its toxic effect through the induction of autophagy in an Akt-dependent fashion without the implication of Mitogen Activated Protein Kinase. Therefore, our data discard the use of inhibitors of the RAF-MEK-ERK1/2 signalling pathway in RCC and support the use of pro-autophagic compounds, opening new therapeutic opportunities for Renal Cell Carcinoma.

Gene expression profiles and pathway enrichment analysis of human osteosarcoma cells exposed to sorafenib

Sorafenib is an inhibitor of a variety of tyrosine kinase receptors used to treat various cancers including hepatocellular, renal cell and thyroid carcinoma. It has been shown to change various targets associated with osteosarcoma, but the detailed mechanism remains unclear. In order to identify key genes, enriched pathways and important modules during the exposure of human osteosarcoma cells to sorafenib, data for gene expression profiles (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE53155) were downloaded from the GEO database. In total, 61 differentially expressed genes (DEGs) were identified by the R bioconductor packages. Functional and enrichment analyses of DEGs were performed using the DAVID database. These revealed that DEGs were enriched in biological processes, molecular function and KEGG pathway of inflammatory immune response and angiogenesis. A protein-protein interaction network was constructed by string and visualized in cytoscape, and eight genes were selected as hubs: IL8,CXCL2,PTGS2,FOS,CXCL1, C3,EHMT2 and PGF. Subsequently, only one cluster was identified by mcode, which consisted of six nodes (CXCL1,CXCL2,PTGS2,FOS, C3 and PGF) and nine edges. PGF was the seed gene in this cluster. In conclusion, the results of this data mining and integration should help in revealing new mechanisms and targets of sorafenib in inhibiting osteosarcoma.

Current and Future Treatment of Hepatocellular Carcinoma: An Updated Comprehensive Review

Hepatocellular carcinoma (HCC) is among the leading causes of cancer-related mortality. The principal treatment is surgical resection or liver transplantation, depending on whether the patient is a suitable transplant candidate. However, in most patients with HCC the diagnosis is often late, thereby excluding the patients from definitive surgical resection. Medical treatment includes sorafenib, which is the most commonly used systemic therapy; although, it has been shown to only minimally impact patient survival by several months. Chemotherapy and radiotherapy are generally ineffective. Due to the poor prognosis of patients with HCC, newer treatments are needed with several being in development, either in pre-clinical or clinical studies. In this review article, we provide an update on the current and future medical and surgical management of HCC.

Impairing energy metabolism in solid tumors through agents targeting oncogenic signaling pathways

Cell metabolic reprogramming is one of the main hallmarks of cancer and many oncogenic pathways that drive the cancer-promoting signals also drive the altered metabolism. This review focuses on recent data on the use of oncogene-targeting agents as potential modulators of deregulated metabolism in different solid cancers. Many drugs, originally designed to inhibit a specific target, then have turned out to have different effects involving also cell metabolism, which may contribute to the mechanisms underlying the growth inhibitory activity of these drugs. Metabolic reprogramming may also represent a way by which cancer cells escape from the selective pressure of targeted drugs and become resistant. Here we discuss how targeting metabolism could emerge as a new effective strategy to overcome such resistance. Finally, accumulating evidence indicates that cancer metabolic rewiring may have profound effects on tumor-infiltrating immune cells. Modulating cancer metabolic pathways through oncogene-targeting agents may not only restore more favorable conditions for proper lymphocytes activation, but also increase the persistence of memory T cells, thereby improving the efficacy of immune-surveillance.

Protein Synthesis Inhibition and Activation of the c-Jun N-Terminal Kinase Are Potential Contributors to Cisplatin Ototoxicity

Cisplatin has been regarded as an effective and versatile chemotherapeutic agent for nearly 40 years. Though the associated dose-dependent ototoxicity is known, the cellular mechanisms by which cochleovestibular hair cell death occur are not well understood. We have previously shown that aminoglycoside ototoxicity is mediated in part by cytosolic protein synthesis inhibition. Despite a lack of molecular similarity, aminoglycosides were shown to elicit similar stress pathways to cisplatin. We therefore reasoned that there may be some role of protein synthesis inhibition in cisplatin ototoxicity. Employing a modification of the bioorthogonal noncanonical amino acid tagging (BONCAT) method, we evaluated the effects of cisplatin on cellular protein synthesis. We show that cisplatin inhibits cellular protein synthesis in organ of Corti explant cultures. Similar to what was found after gentamicin exposure, cisplatin activates both the c-Jun N-terminal kinase (JNK) and mammalian target of rapamycin (mTOR) pathways. In contrast to aminoglycosides, cisplatin also inhibits protein synthesis in all cochlear cell types. We further demonstrate that the multikinase inhibitor sorafenib completely prevents JNK activation, while providing only moderate hair cell protection. Simultaneous stimulation of cellular protein synthesis by insulin, however, significantly improved hair cell survival in culture. The presented data provides evidence for a potential role of protein synthesis inhibition in cisplatin-mediated ototoxicity.

AMP-activated protein kinase - not just an energy sensor

Orthologues of AMP-activated protein kinase (AMPK) occur in essentially all eukaryotes as heterotrimeric complexes comprising catalytic α subunits and regulatory β and γ subunits. The canonical role of AMPK is as an energy sensor, monitoring levels of the nucleotides AMP, ADP, and ATP that bind competitively to the γ subunit. Once activated, AMPK acts to restore energy homeostasis by switching on alternate ATP-generating catabolic pathways while switching off ATP-consuming anabolic pathways. However, its ancestral role in unicellular eukaryotes may have been in sensing of glucose rather than energy. In this article, we discuss a few interesting recent developments in the AMPK field. Firstly, we review recent findings on the canonical pathway by which AMPK is regulated by adenine nucleotides. Secondly, AMPK is now known to be activated in mammalian cells by glucose starvation by a mechanism that occurs in the absence of changes in adenine nucleotides, involving the formation of complexes with Axin and LKB1 on the surface of the lysosome. Thirdly, in addition to containing the nucleotide-binding sites on the γ subunits, AMPK heterotrimers contain a site for binding of allosteric activators termed the allosteric drug and metabolite (ADaM) site. A large number of synthetic activators, some of which show promise as hypoglycaemic agents in pre-clinical studies, have now been shown to bind there. Fourthly, some kinase inhibitors paradoxically activate AMPK, including one (SU6656) that binds in the catalytic site. Finally, although downstream targets originally identified for AMPK were mainly concerned with metabolism, recently identified targets have roles in such diverse areas as mitochondrial fission, integrity of epithelial cell layers, and angiogenesis.

Mechanisms of Paradoxical Activation of AMPK by the Kinase Inhibitors SU6656 and Sorafenib

SU6656, a Src kinase inhibitor, was reported to increase fat oxidation and reduce body weight in mice, with proposed mechanisms involving AMP-activated protein kinase (AMPK) activation via inhibition of phosphorylation of either LKB1 or AMPK by the Src kinase, Fyn. However, we report that AMPK activation by SU6656 is independent of Src kinases or tyrosine phosphorylation of LKB1 or AMPK and is not due to decreased cellular energy status or binding at the ADaM site on AMPK. SU6656 is a potent AMPK inhibitor, yet binding at the catalytic site paradoxically promotes phosphorylation of Thr172 by LKB1. This would enhance phosphorylation of downstream targets provided the lifetime of Thr172 phosphorylation was sufficient to allow dissociation of the inhibitor and subsequent catalysis prior to its dephosphorylation. By contrast, sorafenib, a kinase inhibitor in clinical use, activates AMPK indirectly by inhibiting mitochondrial metabolism and increasing cellular AMP:ADP and/or ADP:ATP ratios.

Improving anti-tumor activity of sorafenib tosylate by lipid- and polymer-coated nanomatrix

In the present study, we select the Sylysia 350 (Sylysia) as mesoporous material, distearoylphosphatidylethanolamine-poly(ethylene glycol)₂₀₀₀ (DSPE-PEG) as absorption enhancer and hydroxy propyl methyl cellulose (HPMC) as crystallization inhibitor to prepare sorafenib tosylate (SFN) nanomitrix (MSNM@SFN) for improving the anti-tumor activity of SFN. The MSNM@SFN was prepared by solvent evaporation method. The solubility, dissolution, and bioavailability of SFN in MSNM@SFN were also investigated. The anti-tumor activity of MSNM@SFN was evaluated in vitro and in vivo. Our results indicated that the solubility and dissolution of SFN in MSNM@SFN were significantly increased. The oral bioavailability of SFN in MSNM@SFN was greatly improved 7.7-fold compared with that in SFN suspension. The enhanced anti-tumor activity of MSNM@SFN was confirmed in vitro and in vivo experiments. This nanomatrix developed in this study could be a promising drug delivery platform for improving the therapeutic efficacy of poorly water-soluble drugs.

Cytoprotective effect of neuropeptides on cancer stem cells: vasoactive intestinal peptide-induced antiapoptotic signaling

Cancer stem cells (CSCs) are increasingly considered to be responsible for tumor initiation, metastasis and drug resistance. The drug resistance mechanisms activated in CSCs have not been thoroughly investigated. Although neuropeptides such as vasoactive intestinal peptide (VIP) can promote tumor growth and activate antiapoptotic signaling in differentiated cancer cells, it is not known whether they can activate antiapoptotic mechanisms in CSCs. The objectives of this study are to unravel the cytoprotective effects of neuropeptides and identify antiapoptotic mechanisms activated by neuropeptides in response to anticancer drug treatment in CSCs. We enriched and purified CSCs (CD44^+/high/CD24^-/low or CD133⁺ population) from breast and prostate cancer cell lines, and demonstrated their stemness phenotype. Of the several neuropeptides tested, only VIP could protect CSCs from drug-induced apoptosis. A functional correlation was found between drug-induced apoptosis and dephosphorylation of proapoptotic Bcl2 family protein BAD. Similarly, VIP-induced cytoprotection correlated with BAD phosphorylation at Ser112 in CSCs. Using pharmacological inhibitors and dominant-negative proteins, we showed that VIP-induced cytoprotection and BAD phosphorylation are mediated via both Ras/MAPK and PKA pathways in CSCs of prostate cancer LNCaP and C4-2 cells, but only PKA signaling was involved in CSCs of DUVIPR (DU145 prostate cancer cells ectopically expressing VIP receptor) and breast cancer MCF7 cells. As each of these pathways partially control BAD phosphorylation at Ser112, both have to be inhibited to block the cytoprotective effects of VIP. Furthermore, VIP is unable to protect CSCs that express phosphorylation-deficient mutant-BAD, suggesting that BAD phosphorylation is essential. Thus, antiapoptotic signaling by VIP could be one of the drug resistance mechanisms by which CSCs escape from anticancer therapies. Our findings suggest the potential usefulness of VIP receptor inhibition to eliminate CSCs, and that targeting BAD might be an attractive strategy for development of novel therapeutics.

The inhibition of FGF receptor 1 activity mediates sorafenib antiproliferative effects in human malignant pleural mesothelioma tumor-initiating cells

Background

Malignant pleural mesothelioma is an aggressive cancer, characterized by rapid progression and high mortality. Persistence of tumor-initiating cells (TICs, or cancer stem cells) after cytotoxic drug treatment is responsible for tumor relapse, and represents one of the main reasons for the poor prognosis of mesothelioma. In fact, identification of the molecules affecting TIC viability is still a significant challenge.

Methods

TIC-enriched cultures were obtained from 10 human malignant pleural mesotheliomas and cultured in vitro. Three fully characterized tumorigenic cultures, named MM1, MM3, and MM4, were selected and used to assess antiproliferative effects of the multi-kinase inhibitor sorafenib. Cell viability was investigated by MTT assay, and cell cycle analysis as well as induction of apoptosis were determined by flow cytometry. Western blotting was performed to reveal the modulation of protein expression and the phosphorylation status of pathways associated with sorafenib treatment.

Results

We analyzed the molecular mechanisms of the antiproliferative effects of sorafenib in mesothelioma TIC cultures. Sorafenib inhibited cell cycle progression in all cultures, but only in MM3 and MM4 cells was this effect associated with Mcl-1-dependent apoptosis. To investigate the mechanisms of sorafenib-mediated antiproliferative activity, TICs were treated with epidermal growth factor (EGF) or basic fibroblast growth factor (bFGF) causing, in MM3 and MM4 cells, MEK, ERK1/2, Akt, and STAT3 phosphorylation. These effects were abolished by sorafenib only in bFGF-treated cells, while a modest inhibition occurred after EGF stimulation, suggesting that sorafenib effects are mainly due to FGF receptor (FGFR) inhibition. Indeed, FGFR1 phosphorylation was inhibited by sorafenib.

Moreover, in MM1 cells, which release high levels of bFGF and showed autocrine activation of FGFR1 and constitutive phosphorylation/activation of MEK-ERK1/2, sorafenib induced a more effective antiproliferative response, confirming that the main target of the drug is the inhibition of FGFR1 activity.

Conclusions

These results suggest that, in malignant pleural mesothelioma TICs, bFGF signaling is the main target of the antiproliferative response of sorafenib, acting directly on the FGFR1 activation. Patients with constitutive FGFR1 activation via an autocrine loop may be more sensitive to sorafenib treatment and the analysis of this possibility warrants further clinical investigation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0573-7) contains supplementary material, which is available to authorized users.

Advantage of sorafenib combined with radiofrequency ablation for treatment of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of death worldwide. Among the surgical and nonsurgical treatments available, radiofrequency ablation (RFA) and sorafenib have been shown to have efficacy. There is little evidence whether combination of these therapies would have additional benefits.

METHODS

In a mouse model of HCC, effects of sorafenib were determined by tumor size, RFA-induced necrosis area (triphenyltetrazolium chloride staining), microvascular density (MVD; 4',6-diamidino-2-phenylindole and anti-CD31 antibody staining), and tumor perfusion (magnetic resonance imaging).

RESULTS

The RFA-induced necrosis area was 80.98 ± 9.14 and 69.49 ± 7.46 mm2 in mice administered 80 and 40 mg/kg sorafenib, respectively, but only 57.29 ± 3.39 mm2 in controls. Sorafenib also reduced tumor volume and enhanced RFA-induced tumor destruction in a dose-dependent manner, and reduced both MVD and tumor perfusion.

CONCLUSIONS

The results of our study suggest a potential role for combining RFA with sorafenib for treatment of HCC. Sorafenib could enhance RFA efficiency, possibly through its angiogenesis suppressive effects.

Targeting Hepatocellular Carcinoma: What did we Discover so Far?

Hepatocellular carcinoma (HCC) is increasingly considered an issue of global importance. Its rates of incidence and mortality have been markedly increasing over the last decades. Among risk factors, some should be highlighted, namely the infections by hepatitis B and C virus, as well as clinical cases of cirrhosis. HCC is characterized as asymptomatic disease in the initial stages which most often leads to a late diagnosis. At molecular and genetic level HCC represents a highly complex tumor entity, including a wide variety of mutations, thus accounting for different mechanisms of resistance towards therapeutic approaches. In particular, mutations of the TP53 gene, as well as a deregulation between the expression of pro- and anti-apoptotic proteins of the BCL-2 family are observed. Regarding treatment modalities, surgical procedures offer the best chance of cure, however, due to a late diagnosis, most of concerned patients cannot be subjected to them. Chemotherapy and radiotherapy are also ineffective, and currently, the treatment with sorafenib is the most commonly used systemic therapy although it can only increase the patient survival for some months. In this sense, a quick and accurate investigation is of utmost importance in order to develop ways of early diagnosis as well as new therapies for HCC.

Sorafenib metabolism, transport, and enterohepatic recycling: physiologically based modeling and simulation in mice

PURPOSE

This study used uncertainty and sensitivity analysis to evaluate a physiologically based pharmacokinetic (PBPK) model of the complex mechanisms of sorafenib and its two main metabolites, sorafenib glucuronide and sorafenib N-oxide in mice.

METHODS

A PBPK model for sorafenib and its two main metabolites was developed to explain disposition in mice. It included relevant influx (Oatp) and efflux (Abcc2 and Abcc3) transporters, hepatic metabolic enzymes (CYP3A4 and UGT1A9), and intestinal β-glucuronidase. Parameterization of drug-specific processes was based on in vitro, ex vivo, and in silico data along with plasma and liver pharmacokinetic data from single and multiple transporter knockout mice.

RESULTS

Uncertainty analysis demonstrated that the model structure and parameter values could explain the observed variability in the pharmacokinetic data. Global sensitivity analysis demonstrated the global effects of metabolizing enzymes on sorafenib and metabolite disposition and the local effects of transporters on their respective substrate exposures. In addition, through hypothesis testing, the model supported that the influx transporter Oatp is a weak substrate for sorafenib and a strong substrate for sorafenib glucuronide and that the efflux transporter Abcc2 is not the only transporter affected in the Abcc2 knockout mouse.

CONCLUSIONS

Translation of the mouse model to humans for the purpose of explaining exceptionally high human pharmacokinetic variability and its relationship with exposure-dependent dose-limiting toxicities will require delineation of the importance of these processes on disposition.

Microenvironmental Targets in Sarcoma

Sarcomas are rare malignant tumors affecting all age groups. They are typically classified according to their resemblance to corresponding normal tissue. Their heterogeneous features, for example, in terms of disease-driving genetic aberrations and body location, complicate both disease classification and development of novel treatment regimens. Many years of failure of improved patient outcome in clinical trials has led to the conclusion that novel targeted therapies are likely needed in combination with current multimodality regimens. Sarcomas have not, in contrast to the common carcinomas, been the subject of larger systematic studies on how tumor behavior relates to characteristics of the tumor microenvironment. There is consequently an urgent need for identifying suitable molecular targets, not only in tumor cells but also in the tumor microenvironment. This review discusses preclinical and clinical data about potential molecular targets in sarcomas. Studies on targeted therapies involving the tumor microenvironment are prioritized. A greater understanding of the biological context is expected to facilitate more successful design of future clinical trials in sarcoma.